Multi-mode hydrogen storage in nanocontainers

Hydrogen can be stored in containers or in materials (in molecular or atomic forms). The atomic form can further exist as multiple phases. Molecular hydrogen can be adsorbed on the surface or can be present inside the material. By invoking multiple modes of hydrogen storage, we establish a paradigm shift in the philosophy of hydrogen storage. Using a novel strategy of storage of molecular hydrogen in metal (Pd) nanocontainers, we observe that 18% hydrogen is in molecular form. Interestingly, this is achieved at 25 °C and 1 atm pressure; which is in contrast to storage in MOFs and carbonaceous materials like nanotubes. Enhancement in storage capacity as compared to Pd nanocrystals of the same mass is observed (36% increase at 1 atm & 25 °C), along with fast kinetics (0.5 wt% hydrogen absorption in 5 s). A new mechanism for hydrogen storage involving the dual catalytic role of Pd is established.     

Preparation and properties of NiFe2O4 nanowires

Polycrystalline NiFe₂O₄ nanowires have been synthesized by PEG assisted co-precipitation method. The formation mechanism of the nanowires proposed is by means of the orientational aggregation of individual nanoparticles. X-ray diffraction, high resolution scanning electron microscopy, transmission electron microscopy, microRaman and vibrating sample magnetometry studies were carried out. The results show that NiFe₂O₄ nanowires were in polycrystalline form with diameter of 58 nm. The synthesized nanowires show room temperature ferromagnetic property with high coercivity. This method is expected to be useful for large scale synthesis of NiFe₂O₄ nanowires for the application of magnetic recording.     

Disclosure of emotional events in groups at risk for posttraumatic stress disorder.

The disclosure of emotional events to various social intimates (disclosure targets) was measured in 2 samples (soldiers and first responders) at risk for posttraumatic stress disorder (PTSD), as well as a comparison sample of college students. These 3 groups completed survey measures of disclosure, and at risk groups also completed measures of PTSD symptoms and social support. Groups at risk for PTSD were less likely to disclose emotions related to potentially traumatic events than were college students reporting general emotional disclosure. Overall, disclosure of positive emotions was more likely than disclosure of negative emotions. Furthermore, amount of disclosure depended on the person to whom the individual disclosed. Within groups at risk for PTSD, social support was associated with lower levels of PTSD. However, this relationship was mediated by emotional disclosure to each target. Disclosure of positive emotions generally was associated with lower levels of PTSD, and disclosure of negative emotions to those with similar at-risk status was associated with greater levels of PTSD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reliability Analysis of Earth Dams

In the present study, results of reliability analyses of four selected rehabilitated earth dam sections, i.e., Chang, Tapar, Rudramata, and Kaswati, under pseudostatic loading conditions, are presented. Using the response surface methodology, in combination with first order reliability method and numerical analysis, the reliability index (β) values are obtained and results are interpreted in conjunction with conventional factor of safety values. The influence of considering variability in the input soil shear strength parameters, horizontal seismic coefficient (αh), and location of reservoir full level on the stability assessment of the earth dam sections is discussed in the probabilistic framework. A comparison of results with those obtained from other method of reliability analysis, viz., Monte Carlo simulations combined with limit equilibrium approach, provided a basis for discussing the stability of earth dams in probabilistic terms, and the results of the analysis suggest that the considered earth dam sections are reliable and are expected to perform satisfactorily.     

Numerical study on mixed convection in a lid-driven cavity with non-uniform heating on both sidewalls

A numerical study has been performed on mixed convection in a lid-driven cavity. The vertical sidewalls of the cavity are maintained with sinusoidal temperature distribution. A finite volume method is used to solve numerically the non-dimensional governing equations. Results are analyzed over a range of the Richardson numbers, amplitude ratios and phase deviations. The results show that heat transfer rate is increased on increasing amplitude ratio. It is observed that average Nusselt numbers are increased first and then decreased when increasing the phase deviation from 0 to π. The non-uniform heating on both walls provides higher heat transfer rate than non-uniform heating of one wall.     

Single basin double slope solar still with minimum basin depth and energy storing materials

Solar still is a simple device which can convert available waste or brackish water into potable water using solar energy. A single basin double slope solar still with an inner basin size 2.08 m × 0.84 m × 0.075 m and that of the outer basin size 2.3 m × 1 m × 0.25 m has been fabricated with mild steel plate and tested with a layer of water and different sensible heat storage materials like quartzite rock, red brick pieces, cement concrete pieces, washed stones and iron scraps. It is found that, the still with ¾ in. sized quartzite rock is the effective basin material. The still is theoretically modeled. In previous researcher’s work, variation in transmittance is taken as constant. The variations in solar incidence angle and transmittance of the covers are also considered in this work. The theoretical values are compared with actual values. The theoretical water and glass temperatures and the theoretical production rate are having higher deviation with actual. Hence, another thermal model developed for this still is applied to validate the results accurately. It is found that, the theoretical production rate using thermal model agrees well with experimental.     

Shelf life extension of fresh fruit and vegetables by chitosan treatment

Among alternatives that are currently under investigation to replace the use of synthetic fungicides to control postharvest diseases in fresh produce and to extend their shelf life, chitosan application has shown promising disease control, at both preharvest and postharvest stages. Chitosan shows a dual mode of action, on the pathogen and on the plant, as it reduces the growth of decay-causing fungi and foodborne pathogens and induces resistance responses in the host tissues. Chitosan coating forms a semipermeable film on the surface of fruit and vegetables, thereby delaying the rate of respiration, decreasing weight loss, maintaining the overall quality, and prolonging the shelf life. Moreover, the coating can provide a substrate for incorporation of other functional food additives, such as minerals, vitamins, or other drugs or nutraceutical compounds that can be used to enhance the beneficial properties of fresh commodities, or in some cases the antimicrobial activity of chitosan. Chitosan coating has been approved as GRAS substance by USFDA, and its application is safe for the consumer and the environment. This review summarizes the most relevant and recent knowledge in the application of chitosan in postharvest disease control and maintenance of overall fruit and vegetable quality during postharvest storage.     

Investigation of Heat Transfer in Serpentine Shaped Microchannel Using Al2O3/Water Nanofluid

An experimental investigation was conducted to explore the maximum heat transfer in a serpentine shaped microchannel by varying the hydraulic diameter, flow rates and with influence of Al₂O₃ nanofluid. Microconvection is an important area in heat transport phenomena. Surface area is one of the important factors in high heat transfer in a microchannel heat exchanger. In this study, serpentine shaped microchannels of hydraulic diameters 810, 830, 860, and 890 μm are analyzed for the optimizing the hydraulic diameter to get enhanced thermal performance of the microchannel. A copper material microchannel having length a of 70 mm is used. Flow rate also varied from 1 lpm (Litres per minute) to 3.5 lpm for optimization with nanofluid as a medium. From numerical study it is observed that as the hydraulic diameter decreases from 890 μm to 810 μm the pressure drop increases with a decrease in hydraulic diameter. Also as heat input to the microchannel increases from 5 watts to 70 watts. From analysis it is observed that the hydraulic diameter of the microchannel is a major factor in microchannel heat transfer which is dependent on flow rate of fluid in the microchannel. The results also show that suspended Al₂O₃ nanoparticles in fluids have enhanced heat transfer when compared to the base fluid.     

Interference based marking method for toric contact eye lens inserts

Toric contact eye lenses are designed to address general blurring that occurs due to uneven cornea which is known as astigmatism. For proper functioning of toric lenses their orientation with respect to the eye is critical. So toric lenses are manufactured with some form of marking which helps in deciding the orientation with respect to the eye. In this research paper a novel marking method based on the interference principle is proposed for toric lenses. Mathematical modeling followed by experiments was done to prove the concept of interference based marking. The proposed marking method is a mask-less, single step clean process.     

High temperature mechanical properties of cryogenically cooled alloy 718 weldments

The micro-segregation of niobium and Laves phase formation during Gas Tungsten Arc (GTA) welding of alloy 718 were studied by employing different cooling techniques which resulted in weld cooling rates ranging from 43.2 °C/s to 508.7 °C/s. The weld cooling rates were achieved by the combinations of modified pulse wave form, argon and helium shielding gases, copper heat sink and liquid nitrogen cooling. A combination of compound current pulse (CCP) waveform with helium shielding and liquid nitrogen cooling resulted in lesser niobium segregation and discontinuous, finer Laves particles in the interdendritic regions compared to that of the conventional constant current GTA weld metal. This process yielded better ageing response and improved high temperature mechanical properties of the weldments.